body waste vs excrement

body waste and excrement both are nouns.

Word	Noun	Adjective	Verb	Adverb
body waste	Yes	No	No	No
excrement	Yes	No	No	No

As nouns, body waste and excrement are synonyms defined as:

body waste and excrement: waste matter (as urine or sweat but especially feces) discharged from the body

Other synonyms of body waste include excreta, excretion, excretory product.

body waste (noun)	excrement (noun)
waste matter (as urine or sweat but especially feces) discharged from the body	waste matter (as urine or sweat but especially feces) discharged from the body